1. Field of the Invention
This invention relates to a system for threading together adjacent individual sections of sheet metal piling and more particularly to a system for threading together adjacent individual sections of sheet metal piling so as to enable workmen to operably thread the adjacent pilings from the ground level position.
2. Description of the Prior Art
In the construction of dams, or other structures wherein sand, cement, earth, or other particulate materials having a tendency to spread must be prevented from so spreading, the use of metal pilings interlocking with other metal pilings to form a wall has been common place.
However, the interlocking of the metal piling sections with one another has been no easy task. A crane is needed to suspend a metal piling over the top edge of an adjacent metal piling so that the edges may be aligned. Once the metal piling edges are aligned, the crane then lowers the metal piling into place. The problem with the alignment is that the metal piling is suspended from a cable wherein the metal piling is movable under stress from winds or lateral movements of the crane. On the other hand, the male interlocking edge must be precisely aligned with the female interlocking edge. Horizontal positions of the edges must coalign. Further, the two pile sections must also be coaligned and not skewed with respect to each other in order for the two pile sections to slide together in an interlocked position. The crane alone cannot adequately align the edge of the suspended piling section with the complementary edge of the set piling section particularly with respect to the skew of the two pile sections.
Conventionally, a man sits on top of the last set piling so he may grab the suspended piling and adequately align the complementary interlocking edges before the crane lowers the set piling into place. The man has to have great agility in sitting on top of a thin metal sheet piling many feet from the ground and subject to unknown factors such as winds, heavy rains, or the direction of the swinging piling. The suspended piling often weighs thousands of pounds and can easily swing and knock the man off his perch. Consequently, because of the risks which are routinely encountered by the man atop the pile sections, construction of pilings is usually halted with the advent of inclement weather which multiplies the risks involved.
Certain safety improvements have been developed to minimize the risks which a man may encounter. One such development is disclosed in the U.S. Pat. No. 2,833,119 issued to Molloy on May 6, 1958. The Molloy patent discloses a safety lock wherein the suspended metal piling has attached to its bottom edge an elongated arm having a pair of spaced arm plates vertically spaced below the elongated arm and extending horizontally upward therefrom. The set piling fits within the space provided and a latch pin extends into the space to latch the bifurcated section of the locking device to the set piling so that the latching device cannot escape outwardly therefrom. The suspended piling is then raised so its lower edge is just above the top edge of the set piling. The man atop the pilings then pulls a handle on the safety lock device so as to align the two interlocking edges. The suspended piling is then lowered with its edge interlocking with the edge of the set piling.
A device which eliminates the use of the man atop the pilings is disclosed in the U.S. Pat. No. 2,583,928 issued to Caudill on Jan. 29, 1952. The Caudill patent discloses a pile threader comprising two halves each connected to a draw bar. The two halves are connected and clamped onto the lower edge of a suspended pile section. The pair of draw bars have rollers at the ends thereof. At the other ends, an eccentrically placed cam lever is mounted thereto. The rollers engage a narrow portion of the male interlocking edge of the set piling section. A crane is used to elevate the suspended piling so its lower edge is above the top edge of the set piling. The cam lever is pulled down to move the plates that are connected to the suspended piling over toward the set piling so that the female edge of the suspended piling is aligned directly over the set piles on the male interlocking edge. The crane lowers the suspended piling so that the edges interlock. The process is then repeated as often as necessary.
Conventionally, the crane suspends the piling sections by the use of a clamp. The clamp must releasably engage the pile section as well as secure the piling without risks of slippage. A clamp used to lift heavy metal plates is disclosed in the U.S. Pat. No. 3,088,749 issued to Gowan on Nov. 14, 1961. The Gowan clamp has a pair of pinching rollers. The pinching rollers are operatively connected to a lever arm. The lever arm when in a downward position locks the pinching rollers and releases the pinching rollers when in an upward position.